From Clarity to Efficiency for Distributed Algorithms

27/03/2013Intervenant(s) : Annie Liu (Stony Brook U., USA)This talk describes a very high-level language for clear description of distributed algorithms and optimizations necessary for generating efficient implementations. The language supports high-level control flows where complex synchronization conditions can be expressed using high-level queries---especially logic quantifications---over message history sequences. This greatly facilitates algorithm understanding and correctness proofs. Unfortunately, the programs would be extremely inefficient, including consuming unbounded memory, if executed straightforwardly.We present new optimizations that automatically transform complex synchronization conditions into incremental updates of necessary auxiliary values as messages are sent and received. The core of the optimizations is the first general method for efficient implementation of logic quantifications. We have developed an operational semantics of the language, implemented a prototype of the compiler and the optimizations, and successfully used the language and implementation on a variety of important distributed algorithms. This also led to improvements to some of the algorithms, both for correctness and for optimizations.